Enhanced electromagnetic coupling between a transmission line pair with reduced electromagnetic coupling to ground

Abstract

According to one exemplary embodiment, a circuit board for reducing dielectric loss, conductor loss, and insertion loss includes a pair of transmission lines. The pair of transmission lines has sufficient thickness to cause substantial broadside electromagnetic coupling between the pair of transmission lines, where the pair of transmission lines is sufficiently separated from a ground plane of the circuit board so as to cause negligible electromagnetic coupling to the ground plane relative to the substantial broadside electromagnetic coupling. The pair of transmission lines thereby reduce dielectric loss, conductor loss, and insertion loss for signals traversing through the transmission line pair. The pair of transmission lines can be separated from the ground plane by, for example, at least 50.0 mils.

The invention claimed is: 
     
       1. An Ethernet card for reducing dielectric loss, conductor loss, and insertion loss for signals traversing through a pair of transmission lines in said Ethernet card, said Ethernet card comprising:
 said pair of transmission lines having a thickness to increase broadside electromagnetic coupling between said pair of transmission lines relative to electromagnetic coupling of said pair of transmission lines to a ground plane of said Ethernet card; 
 said pair of transmission lines being separated from said ground plane of said Ethernet card by at least 50 mils so as to reduce electromagnetic coupling to said ground plane of said Ethernet card relative to said broadside electromagnetic coupling. 
 
     
     
       2. The Ethernet card of  claim 1 , wherein said pair of transmission lines is a differential pair. 
     
     
       3. The Ethernet card of  claim 1 , wherein said pair of transmission lines is a co-planar pair. 
     
     
       4. The Ethernet card of  claim 1 , wherein said thickness of said pair of transmission lines is between approximately 1.9 mils and approximately 5.3 mils. 
     
     
       5. The Ethernet card of  claim 1 , wherein said ground plane of said Ethernet card is situated on a bottom surface of said Ethernet card. 
     
     
       6. The Ethernet card of  claim 1 , wherein each of said pair of transmission lines has a width of between approximately 2.0 mils and approximately 8.0 mils. 
     
     
       7. The Ethernet card of  claim 1 , wherein said Ethernet card comprises FR-4. 
     
     
       8. The Ethernet card of  claim 1 , wherein said pair of transmission lines comprises copper. 
     
     
       9. An optical switch card for reducing dielectric loss, conductor loss, and insertion loss for signals traversing through a pair of transmission lines in said optical switch card, said optical switch card comprising:
 said pair of transmission lines having a thickness to increase broadside electromagnetic coupling between said pair of transmission lines relative to electromagnetic coupling of said pair of transmission lines to a ground plane of said optical switch card; 
 said pair of transmission lines being separated from said ground plane of said optical switch card by at least 50 mils so as to reduce electromagnetic coupling to said ground plane of said optical switch card relative to said broadside electromagnetic coupling. 
 
     
     
       10. The optical switch card of  claim 9 , wherein said pair of transmission lines drive an input/output port of said optical switch card. 
     
     
       11. The optical switch card of  claim 10 , wherein said input/output port of said optical switch card is connected to an optical module. 
     
     
       12. The optical switch card of  claim 9 , wherein said pair of transmission lines is a differential pair. 
     
     
       13. The optical switch card of  claim 9 , wherein said pair of transmission lines is a co-planar pair. 
     
     
       14. The optical switch card of  claim 9 , wherein said thickness of said pair of transmission lines is between approximately 1.9 mils and approximately 5.3 mils. 
     
     
       15. The optical switch card of  claim 9 , wherein said ground plane of said optical switch card is situated on a bottom surface of said optical switch card. 
     
     
       16. The optical switch card of  claim 9 , wherein each of said pair of transmission lines has a width of between approximately 2.0 mils and approximately 8.0 mils. 
     
     
       17. The optical switch card of  claim 9 , wherein said optical switch card comprises FR-4. 
     
     
       18. The optical switch card of  claim 9 , wherein said pair of transmission lines comprises copper.